1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition useful for microfabrication using various types of radiation, in particular, such as far ultraviolet rays represented by a KrF excimer laser, charged particle rays such as electron beams, and X-rays such as synchrotron radiation.
2. Description of Background Art
As a resist applicable to far ultraviolet rays such as a KrF excimer laser, charged particle rays such as electron beams, and X-rays such as synchrotron radiation, a chemically-amplified resist comprising a photoacid generator which can increase the sensitivity by the catalytic action of an acid formed by the photoacid generator upon irradiation with radioactive rays (hereinafter called xe2x80x9cexposurexe2x80x9d) has been proposed.
The following problem has been pointed out for conventional chemically-amplified resists. Specifically, because of the time delay from exposure to heating after exposure (hereinafter referred to as xe2x80x9cPEDxe2x80x9d), the line width of the resist pattern varies or the resist pattern changes into a T-shape. In recent years, various chemically-amplified resists which can be applied to the manufacture of semiconductor devices have been proposed. For example, Japanese Patent Application Laid-open No. 209868/1995 has disclosed a chemically-amplified radiation-sensitive resin composition comprising a polymer which comprises a hydroxystyrene recurring unit, a t-butyl (meth)acrylate recurring unit, and a recurring unit which reduces the solubility of the polymer in an alkaline developer after exposure.
However, as the design dimensions of the devices become more minute such as half micron or less, the chemically amplified resist exhibits defects during development (xe2x80x9cdefective developmentxe2x80x9d) such as development failure in the minute pattern, fall down of the pattern, and changes in the line width due to unevenness in the solubility of the exposed area in the developer to decrease the yield.
In view of the above situation of the conventional technology, an object of the present invention is to provide a radiation-sensitive resin composition useful as a chemically-amplified resist which exhibits no defective development, and does not cause the line width to change nor the resist pattern to change into a T-shape due to PED. Another object of the present invention is to provide a radiation-sensitive resin composition which exhibits high sensitivity to various radiations such as far ultraviolet rays such as a KrF excimer laser, charged particle rays such as electron beams, and X-rays such as synchrotron radiation and exhibits superior resolution.
According to the present invention, the above objects can be achieved by a radiation-sensitive resin composition comprising:
(A) a resin which comprises a recurring unit (1) shown by the following formula (1) and either or both of a recurring unit (2) shown by the following formula (2) and a recurring unit (3) shown by the following formula (3): 
wherein R1 represents a hydrogen atom or a methyl group; 
wherein R2 represents a hydrogen atom or a methyl group and R3 represents a tertiary alkyl group having 4-10 carbon atoms or a 1,1-dimethyl-3-oxobutyl group; 
wherein R4 represents a hydrogen atom or a methyl group and R5 represents a t-butyl group or acetyl group; and
(B) a photoacid generator shown by the following formula 
wherein (a) R6-R11 individually represent a hydrogen atom or a monovalent organic group having 1-6 carbon atoms, provided that at least one of R6-R11 represents a group other than a hydrogen atom; provided further that, (b) two among R6-R8 may form a 3-8 membered cyclic structure together with the carbon atoms of the benzene ring to which these groups are bonded, (c) R9-R11 may form a 3-8 membered cyclic structure together with the carbon atoms in the benzene ring to which these groups are bonded, or (d) two among R6-R8 may form a 3-8 membered cyclic structure together with the carbon atoms of the benzene ring to which these groups are bonded and two among R9-R11 may form a 3-8 membered cyclic structure together with the carbon atoms in the benzene ring to which these groups are bonded.
Other objects, features and advantages of the invention will hereinafter become more readily apparent from the following description.
The present invention will be described in detail.
(A) Resin
The component (A) of the present invention is a resin comprising the recurring unit (1) and either the recurring unit (2) or the recurring unit (3), or both (hereinafter referred to as xe2x80x9cresin (A)xe2x80x9d).
As the recurring unit (1), units derived from p-hydroxystyrene and the like are particularly preferable.
In the formula (2) which shows the recurring unit (2), examples of a tertiary alkyl group having 4-10 carbon atoms represented by R3 include a t-butyl group, 1,1-dimethylpropyl group, 1-methyl-1-ethylpropyl group, 1,1-diethylpropyl group, 1,1-dimethylbutyl group, 1-methyl-1-ethylbutyl group, 1,1-diethylbutyl group, 1,1-dimethylpentyl group, 1-methyl-1-ethylpentyl group, 1,1-diethylpentyl group, 1,1-dimethylhexyl group, 1-methyl-1-ethylhexyl group, 1,1-diethylhexyl group, 1,1-dimethylheptyl group, 1-methyl-1-ethylheptyl group, 1,1-dimethyloctyl group, and the like.
A t-butyl group, 1,1-dimethylpropyl group, 1,1-dimethyl-3-oxobutyl group (xe2x80x94C (CH3)2CH2C(xe2x95x90O) CH3), and the like are particularly preferable as R3.
As the recurring unit (3), units derived from p-t-butoxystyrene, p-acetyloxystyrene, and the like are preferable. P-t-butoxystyrene is particularly preferable.
In the resin (A), various types of groups for the recurring units (1), (2), and (3) mentioned above may be used either individually or in combinations of two or more.
The resin (A) can comprise at least one recurring unit other than the recurring units (1), (2), and (3) (hereinafter referred to as xe2x80x9cother recurring unitsxe2x80x9d).
Among monomers which can be used as the other recurring units, examples of monofunctional monomers having one polymerizable unsaturated group in the molecule include vinyl aromatic compounds such as styrene, xcex1-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-methoxystyrene, m-methoxystyrene, and p-methoxystyrene; unsaturated carboxylic acids or acid anhydrides thereof such as (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, mesaconic acid, citraconic acid, itaconic acid, maleic anhydride, and citraconic anhydride; esters such as methyl ester, ethyl ester, n-propyl ester, i-propyl ester, n-butyl ester, i-butyl ester, sec-butyl ester, t-butyl ester (excluding t-butyl (meth)acrylate), N-amyl ester, n-hexyl ester, cyclohexyl ester, 2-hydroxyethyl ester, 2-hydroxypropyl ester, 3-hydroxypropyl ester, 2,2-dimethyl-3-hydroxypropyl ester, benzyl ester, isobornyl ester, tricyclodecanyl ester, and 1-adamantyl ester of the above unsaturated carboxylic acids; unsaturated nitriles such as (meth)acrylonitrile, maleinitrile, fumarnitrile, mesaconitrile, citraconitrile, and itaconitrile; unsaturated amides such as (meth)acrylamide, crotonamide, maleinamide, fumaramide, mesaconamide, citraconamide, and itaconamide; unsaturated imides such as maleimide, N-phenylmaleimide, and N-cyclohexylmaleimide; unsaturated alcohols such as (meth)allyl alcohol; N-vinylaniline, vinylpyridines, N-vinyl-xcex5-caprolactam, N-vinylpyrrolidone, N-vinylimidazole, N-vinylcarbazole; and the like.
Of these monofunctional monomers, vinyl aromatic compounds and esters of unsaturated carboxylic acids are preferable. Styrene, methyl (meth)acrylate, and the like are particularly preferable.
Among monomers which can be used as the other recurring units, examples of polyfunctional monomers having two or more polymerizable unsaturated groups in the molecule include esters of a compound having two or more hydroxyl groups in the molecule (such as polyhydric alcohols, polyether diol, and polyester diol) and (meth)acrylic acid; addition products of a compound having two or more epoxy groups in the molecule, such as an epoxy resin, and (meth)acrylic acid; condensation products of a compound having two or more amino groups in the molecule and (meth)acrylic acid; and the like. Specific examples include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, 2,5-dimethyl-2,5-hexanediol di(meth)acrylate, N,Nxe2x80x2-methylenebis(meth)acrylamide, (poly)alkylene glycol (derivative) di(meth)acrylates such as di(meth)acrylates of ethylene glycol or propylene glycol addition products of bisphenol A, epoxy (meth)acrylates such as di(meth)acrylic acid addition product of bisphenol A diglycidyl ether, and the like.
Of these polyfunctional monomers, ethylene glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, 2,5-dimethyl-2,5-hexanediol di(meth)acrylate, di(meth)acrylic acid addition product of bisphenol A diglycidyl ether, and the like are particularly preferable.
An moderate crosslinking structure can be introduced into the resin (A) by using the polyfunctional monomers as the monomer for the other recurring units. This decreases the motility of the polymer molecular chain and hinders heat deformation, thereby improving heat resistance and the like. If the crosslinking structure introduced by the polyfunctional monomer exhibits acid-decomposability, the molecular weight is reduced upon exposure to a greater extent than in the case of a linear resin or in the case where the crosslinking structure does not exhibit acid-decomposability. Because of this, the difference in the dissolution rate in a developer between the exposed area and the unexposed area increases, whereby the resolution can be further improved.
In the following description, the resin (A) comprising the recurring units (1) and (2) and the other recurring units, as required, is referred to as xe2x80x9cresin (A1)xe2x80x9d, the resin (A) comprising the recurring units (1) and (3) and the other recurring units, as required, is referred to as xe2x80x9cresin (A2)xe2x80x9d, and the resin (A) comprising the recurring units (1), (2), and (3) and the other recurring units, as required, is referred to as xe2x80x9cresin (A3)xe2x80x9d.
As specific examples of the preferable resin (A) of the present invention, copolymers made from the following combinations of monomers can be given.
Resin (A1)
p-hydroxystyrene/t-butyl (meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate copolymer,
p-hydroxystyrene/t-butyl (meth)acrylate/styrene copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate/styrene copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate/styrene copolymer,
p-hydroxystyrene/t-butyl (meth)acrylate/methyl (meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate/methyl (meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate/methyl (meth)acrylate copolymer,
p-hydroxystyrene/t-butyl (meth)acrylate/ethylene glycol di(meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate/ethylene glycol di(meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate/ethylene glycol di(meth)acrylate copolymer,
p-hydroxystyrene/t-butyl (meth)acrylate/tricyclodecanedimethanol di(meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate/tricyclodecanedimethanol di(meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate/tricyclodecanedimethanol di(meth)acrylate copolymer,
p-hydroxystyrene/t-butyl (meth)acrylate/di(meth)acrylic acid addition product of bisphenol A diglycidyl ether copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate/di(meth)acrylic acid addition product of bisphenol A diglycidyl ether copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate/di(meth)acrylic acid addition product of bisphenol A diglycidyl ether copolymer copolymer,
p-hydroxystyrene/t-butyl (meth)acrylate/2,5-dimethyl-2,5-hexanediol di(meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethylpropyl (meth)acrylate/2,5-dimethyl-2,5-hexanediol di(meth)acrylate copolymer,
p-hydroxystyrene/1,1-dimethyl-3-oxobutyl (meth)acrylate/2,5-dimethyl-2,5-hexanediol di(meth)acrylate copolymer.
Resin (A2)
p-hydroxystyrene/p-t-butoxystyrene copolymer,
p-hydroxystyrene/p-acetoxystyrene copolymer,
p-hydroxystyrene/p-t-butoxystyrene/styrene copolymer,
p-hydroxystyrene/p-acetoxystyrene/styrene copolymer,
p-hydroxystyrene/p-t-butoxystyrene/methyl (meth)acrylate copolymer,
p-hydroxystyrene/p-acetoxystyrene/methyl (meth)acrylate copolymer,
p-hydroxystyrene/p-t-butoxystyrene/ethylene glycol di(meth)acrylate copolymer,
p-hydroxystyrene/p-acetoxystyrene/ethylene glycol di(meth)acrylate copolymer,
p-hydroxystyrene/p-t-butoxystyrene/tricyclodecanedimethanol di(meth)acrylate copolymer,
p-hydroxystyrene/p-acetoxystyrene/tricyclodecanedimethanol di(meth)acrylate copolymer,
p-hydroxystyrene/p-t-butoxystyrene/di(meth)acrylic acid addition product of bisphenol A diglycidyl ether copolymer,
p-hydroxystyrene/p-acetoxystyrene/di(meth)acrylic acid addition product of bisphenol A diglycidyl ether copolymer,
p-hydroxystyrene/p-t-butoxystyrene/2,5-dimethyl-2,5-hexanediol di(meth)acrylate copolymer,
p-hydroxystyrene/p-acetoxystyrene/2,5-dimethyl-2,5-hexanediol di(meth)acrylate copolymer.
The content of each recurring unit in the resin (A) is as follows.
The content of the recurring unit (1) in the resin (A1), (A2), and (A3) is usually 30-90 mol %, and preferably 50-85 mol % for the total amount of the recurring units (1), (2), and (3).
The content of the recurring unit (2) in the resin (A1) is usually 5-70 mol %, and preferably 5-50 mol % for the total amount of the recurring units (1) and (2). The content of the recurring unit (3) in the resin (A2) is usually 10-50 mol %, and preferably 15-40 mol % for the total amount of the recurring units (1) and (3). The total content of the recurring units (2) and (3) in the resin (A3) is usually5-70 mol %, and preferably 5-50 mol % for the total amount of the recurring units (1), (2), and (3).
The content of the other recurring units derived from the monofunctional monomers is usually 50 mol % or less, and preferably 40 mol % or less for the total amount of all recurring units. The content of the other recurring unit derived from the polyfunctional monomers is usually 15 wt % or less, and preferably 10 wt % or less for the amount of each resin.
If the content of the recurring unit (1) in each of the resins (A1), (A2), and (A3) is less than 30 mol %, sensitivity as a resist tends to decrease. If the content exceeds 90 mol %, resolution as a resist tends to decrease.
If the content of the recurring unit (2) in the resin (A1) is less than 5 mol %, or if the content of the recurring unit (3) in the resin (A2) is less than 10 mol %, or if the total content of the recurring units (2) and (3) in the resin (A3) is less than 5 mol %, resolution as a resist tends to decrease. If the content of the recurring unit (2) in the resin (A1) exceeds 70 mol %, or if the content of the recurring unit (3) in the resin (A2) exceeds 50 mol %, or if the total content of the recurring units (2) and (3) in the resin (A3) exceeds 70 mol %, sensitivity as a resist tends to decrease.
If the content of the other recurring units derived from the monofunctional monomers in each of the resins (A1), (A2), and (A3) exceeds 50 mol %, resolution as a resist tends to decrease. If the content of the other recurring unit derived from the polyfunctional monomers in the resins (A1), (A2), and (A3) exceeds 15 wt %, solubility in a developer tends to decrease.
The resin (A) is manufactured by, for example, the following methods (a)-(e).
(a) A method of copolymerizing a monomer corresponding to the recurring unit (1) and a monomer corresponding to the recurring unit (2) or a monomer corresponding to the recurring unit (3), or both, together with a monomer corresponding to the other recurring unit, as required, by block polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, block-suspension polymerization, or the like using an appropriate radical polymerization initiator, or copolymerizing these monomers by cationic polymerization.
(b) A method of copolymerizing t-butoxystyrenes and a monomer corresponding to the recurring unit (2) together with a monomer corresponding to the other recurring unit, as required, by block polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, block-suspension polymerization, or the like using an appropriate radical polymerization initiator, for example, or copolymerizing the monomers by living anionic polymerization and selectively hydrolyzing and/or solvolyzing at least part of t-butyl groups in the copolymer using an acid catalyst.
(c) A method of copolymerizing acetoxystyrenes and a monomer corresponding to the recurring unit (2) together with a monomer corresponding to the other recurring unit, as required, by block polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, block-suspension polymerization, or the like using an appropriate radical polymerization initiator, and selectively hydrolyzing and/or solvolyzing at least part of acetyl groups in the copolymer using a basic catalyst.
(d) A method of copolymerizing t-butoxystyrenes together with a monomer corresponding to the other recurring unit, as required, by block polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, block-suspension polymerization, or the like using an appropriate radical polymerization initiator, for example, or copolymerizing the monomers by living anionic polymerization and selectively hydrolyzing and/or solvolyzing part of t-butyl groups in the copolymer using an acid catalyst.
(e) A method of copolymerizing acetoxystyrenes together with a monomer corresponding to the other recurring unit, as required, by block polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, block-suspension polymerization, or the like using an appropriate radical polymerization initiator, and selectively hydrolyzing and/or solvolyzing part of acetyl groups in the copolymer using a basic catalyst.
The polystyrene-reduced weight average molecular weight of the resin (A) determined by gel permeation chromatography (GPC) (hereinafter referred to as xe2x80x9cMwxe2x80x9d) is as follows. The Mw of the resin (A) having no crosslinking structure introduced by the polyfunctional monomer is usually 1,000-100,000, preferably 3,000-40,000, and still more preferably 3,000-30,000. If the Mw of the resin (A) is less than 1,000, sensitivity and heat resistance as a resist tend to decrease. If the Mw exceeds 100,000, solubility in a developer tends to decrease.
The ratio of Mw of the resin (A) having no crosslinking structure introduced by the polyfunctional monomer to the polystyrene-reduced number average molecular weight (hereinafter referred to as xe2x80x9cMnxe2x80x9d) determined by gel permeation chromatography (GPC) (Mw/Mn) is usually 1.0-5.0, preferably 1.0-4.0, and still more preferably 1.0-3.0.
The Mw of the resin (A) having a crosslinking structure introduced by the polyfunctional monomer is usually 3,000-500,000, preferably 5,000-400,000, and still more preferably 8,000-300,000. If the Mw of the resin (A) is less than 3,000, sensitivity and heat resistance as a resist tend to decrease. If the Mw exceeds 500,000, the effect of inhibiting the defective development tends to decrease.
The Mw/Mn of the resin (A) having a crosslinking structure introduced by the polyfunctional monomer is usually 1.5-20.0, and preferably 1.5-15.0.
In the present invention, the resin (A) may comprise other resins (for example, poly(hydroxystyrene)) or compounds with a low molecular weight (for example, 2,2-bis(4-t-butoxyphenyl)propane) which do not impair the uniformity of the coating film formed on the substrate and exhibit compatibility with the resin (A). The total amount of such other resins and low-molecular weight compounds is preferably 50 parts by weight or less for 100 parts by weight of the resin (A).
Photoacid Generator (B)
The component (B) of the present invention is a compound which is shown by the formula (4) and generates an acid upon exposure (hereinafter referred to as xe2x80x9cacid generator (B)xe2x80x9d).
As specific examples of a monovalent organic group having 1-6 carbon atoms for R6-R11 in the formula (4), an alkyl group such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, t-amyl group, 1,1-dimethylpropyl group, n-hexyl group, and 1,1-dimethylbutyl group; an alkoxyl group such as a methoxy group, ethoxygroup, n-propoxygroup, i-propoxygroup, n-butoxy group, i-butoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, and n-hexyloxy group; an alkoxyalkyl group such as a methoxymethyl group, ethoxymethyl group, 1-methoxyethyl group, 2-methoxyethyl group, 1-ethoxyethyl group, 2-ethoxyethyl group, 3-methoxypropyl group, 3-ethoxypropyl group, 4-methoxybutyl group, and 4-ethoxybutyl group; an alkoxyalkoxyl group such as a methoxymethoxy group, ethoxymethoxy group, 1-methoxyethoxy group, 2-methoxyethoxy group, 1-ethoxyethoxy group, 2-ethoxyethoxy group, 3-methoxypropoxy group, 3-ethoxypropoxy group, 4-methoxybutoxy group, and 4-ethoxybutoxy group; a cyano group; a carboxyl group; xe2x80x94COOX (wherein X represents an alkyl group having 1-5 carbon atoms); a dialkylamino group (wherein the total number of carbon atoms of an alkyl group is 2-6); and the like can be given.
Of these monovalent organic groups, a methyl group, ethyl group, i-propyl group, t-butyl group, t-amyl group, methoxy group, ethoxy group, i-propoxy group, t-butoxy group, methoxymethyl group, ethoxymethyl group, 1-methoxyethyl group, 1-ethoxyethyl group, methoxymethoxy group, ethoxymethoxy group, 1-methoxyethoxy group, 1-ethoxyethoxy group, and the like are preferable.
The 3-8 membered cyclic structure formed by two among R6-R8 bonded together with the carbon atoms which constitutes the benzene ring and the 3-8 membered cyclic structure formed by two among R9-R11 bonded together with the carbon atoms which constitutes the benzene ring may be a carbocyclic ring or a heterocyclic ring comprising at least one hetero-atom such as a nitrogen atom, oxygen atom, and sulphur atom.
As the above 3-8 membered cyclic structures, a 5-6 membered carbocyclic structure formed with adjacent two carbon atoms which constitute the benzene ring, a 5-6 membered heterocyclic structure which comprises one or two oxygen atoms as a hetero-atom and is formed with adjacent two carbon atoms which constitute the benzene ring, and the like are preferable.
As specific examples of preferable acid generator (B) of the present invention, compounds shown by the following formulas (5)-(58) and the like can be given. 
Of these acid generators (B), the compounds shown by the formulas (5), (6), (10), (11), (12), (13), (14), (15), (16), (19), (23), (25), (29), (31), (32), (34), (35), (36), (37), (38), (39), (40), (41), (42), and (54) are particularly preferable.
In the present invention, the acid generator (B) can be used either individually or in combinations of two or more.
The amount of the acid generator (B) to be used in the present invention is usually 0.3-20 parts by weight, and preferably 0.5-10 parts by weight, for 100 parts by weight of the resin (A). If the amount of the acid generator (B) is less than 0.3 part by weight, the effect of inhibiting the defective development tends to be insufficient or the chemical change by the catalytic action of the acid generated upon exposure tends to be insufficient. If the amount exceeds 20 parts by weight, application of the composition may become uneven or scum or the like tends to occur at the time of development.
In the present invention, the following photoacid generators (hereinafter referred to as xe2x80x9cother acid generatorsxe2x80x9d) can be used in combination with the acid generator (B).
As examples of the other acid generators, onium salt compounds, sulfone compounds, sulfonate compounds, sulfonimide compounds, diazomethane compounds, and the like can be given.
Specific examples of these other acid generators are given below.
Onium Salt Compounds
Specific examples of the onium salt compounds include
bis(4-t-butylphenyl)iodonium perfluoro-n-butanesulfonate,
bis(4-t-butylphenyl)iodonium 2-trifluoromethylbenzenesulfonate,
bis(4-t-butylphenyl)iodonium pyrenesulfonate,
bis(4-t-butylphenyl)iodonium n-dodecylbenzenesulfonate,
bis(4-t-butylphenyl)iodonium p-toluenesulfonate, bis(4-t-butylphenyl)iodonium benzenesulfonate,
bis(4-t-butylphenyl)iodonium 10-camphorsulfonate, bis(4-t-butylphenyl)iodonium n-octanesulfonate, diphenyliodonium perfluoro-n-butanesulfonate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium 2-trifluoromethylbenzenesulfonate, diphenyliodonium pyrenesulfonate,
diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium p-toluenesulfonate,
diphenyliodonium benzenesulfonate,
diphenyliodonium 10-camphorsulfonate,
diphenyliodonium n-octanesulfonate,
triphenylsulfonium perfluoro-n-butanesulfonate,
triphenylsulfonium trifluoromethanesulfonate,
triphenylsulfonium 2-trifluoromethylbenzenesulfonate,
triphenylsulfonium pyrenesulfonate,
triphenylsulfonium n-dodecylbenzenesulfonate,
triphenylsulfonium p-toluenesulfonate, triphenylsulfonium benzenesulfonate, triphenylsulfonium 10-camphorsulfonate,
triphenylsulfonium n-octanesulfonate,
4-t-butylphenyl-diphenylsulfonium perfluoro-n-butanesulfonate,
4-t-butylphenyl-diphenylsulfonium trifluoromethanesulfonate,
4-t-butylphenyl-diphenylsulfonium 2-trifluoromethylbenzenesulfonate,
4-t-butoxyphenyl-diphenylsulfonium pyrenesulfonate, 4-t-butoxyphenyl-diphenylsulfonium n-dodecylbenzenesulfonate,
4-t-butoxyphenyl-diphenylsulfonium p-toluenesulfonate, 4-t-butoxyphenyl-diphenylsulfonium benzenesulfonate, 4-t-butoxyphenyl-diphenylsulfonium 10-camphorsulfonate, 4-t-butoxyphenyl-diphenylsulfonium n-octanesulfonate, and the like.
Sulfone Compounds
Specific examples of the sulfone compounds include phenacylphenylsulfone, mesitylphenacylsulfone, bis(phenylsulfonyl)methane, 4-trisphenacylsulfone, and the like.
Sulfonate Compounds
Specific examples of the sulfonate compounds include xcex1-methylolbenzoin perfluoro-n-butanesulfonate, xcex1-methylolbenzoin trifluoromethanesulfonate, xcex1-methylolbenzoin 2-trifluoromethylbenzenesulfonate, benzointosylate, methanesulfonic acid triester of pyrogallol, nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, xcex1-methylolbenzointosylate, xcex1-methylolbenzoin n-octanesulfonate, xcex1-methylolbenzoin n-dodecylbenzenesulfonate, and the like.
Sulfonimide Compounds
Specific examples of the sulfonimide compounds include
N-(perfluoro-n-butylsulfonyloxy)succinimide, N-(perfluoro-n-butylsulfonyloxy)phthalimide,
N-(perfluoro-n-butylsulfonyloxy)diphenylmaleimide,
N-(perfluoro-n-butylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(perfluoro-n-butylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(perfluoro-n-butylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,
N-(perfluoro-n-butylsulfonyloxy)naphthylimide,
N-(trifluoromethylsulfonyloxy)succinimide,
N-(trifluoromethylsulfonyloxy)phthalimide,
N-(trifluoromethylsulfonyloxy)diphenylmaleimide,
N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(trifluoromethylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,
N-(trifluoromethylsulfonyloxy)naphthylimide,
N-(2-trifluoromethylphenylsulfonyloxy)succinimide,
N-(2-trifluoromethylphenylsulfonyloxy)phthalimide, N-(2-trifluoromethylphenylsulfonyloxy)diphenylmaleimide,
N-(2-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimido,
N-(2-trifluoromethylphenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(2-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,
N-(2-trifluoromethylphenylsulfonyloxy)naphthylimide,
N-(10-camphanylsulfonyloxy)succinimide,
N-(10-camphanylsulfonyloxy)phthalimide,
N-(10-camphanylsulfonyloxy)diphenylmaleimide,
N-(10-camphanylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide, N-(10-camphanylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(10-camphanylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,
N-(10-camphanylsulfonyloxy)aphthylimide,
N-(4-methylphenylsulfonyloxy)succinimide,
N-(4-methylphenylsulfonyloxy)phthalimide,
N-(4-methylphenylsulfonyloxy)diphenylmaleimide,
N-(4-methylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(4-methylphenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(4-methylphenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,
N-(4-methylphenylsulfonyloxy)naphthylimide,
N-(n-octylsulfonyloxy)succinimide,
N-(n-octylsulfonyloxy)phthalimide,
N-(n-octylsulfonyloxy)diphenylmaleimide,
N-(n-octylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide, N-(n-octylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(n-octylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,
N-(n-octylsulfonyloxy)naphthylimide, and the like.
Disulfonylmethane Compounds
As examples of the disulfonylmethane compounds, compounds shown by the following formula (59) and the like can be given. 
wherein R12 and R13 individually represent an acyclic hydrocarbon group having 1-10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3-10 carbon atoms, a substituted or unsubstituted aryl group having 6-20 carbon atoms, a substituted or unsubstituted aralkyl group having 7-20 carbon atoms, or other monovalent organic groups having a hetero-atom and 1-20 carbon atoms.
The proportion of the other acid generators to be used in the present invention is less than 20 times, and preferably 15 times or less the amount of the acid generator (B) in a molar ratio. If the proportion of the other acid generators exceeds this limit, the effect of inhibiting the defective development may be insufficient.
Acid Diffusion Controller
In the present invention, it is preferable to blend in an acid diffusion controller which controls the diffusion of an acid generated in the resist film by the acid generator (B) and the other acid generators upon exposure, and hinders the unfavorable chemical reaction in the unexposed area. Use of such an acid diffusion controller improves the storage stability of the composition and resolution as a resist. Moreover, line width change of the resist pattern due to PED can be controlled, whereby remarkably superior process stability can be achieved. As the acid diffusion controller, nitrogen-containing organic compounds of which the basicity does not change when exposed or heated are preferable. Specific examples of such organic compounds include compounds shown by the formula R14R15R16N (wherein R14, R15, and R16 individually represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or substituted or unsubstituted aralkyl group) (hereinafter referred to as xe2x80x9cnitrogen-containing compound (I)xe2x80x9d), diamino compounds having two nitrogen atoms in the molecule (hereinafter referred to as xe2x80x9cnitrogen-containing compound (II)xe2x80x9d), polymers having at least three nitrogen atoms (hereinafter referred to as xe2x80x9cnitrogen-containing compound (III)xe2x80x9d), compounds containing an amide group, urea compounds, heterocyclic compounds containing nitrogen, and the like.
Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, and monoethanolamine; dialkylamines such as di-n-butylamine, di-n-pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine, di-n-nonylamine, di-n-decylamine, and diethanolamine; trialkylamines such as triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, and triethanolamine; and aromatic amines such as aniline, N-methylaniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, diphenylamine, triphenylamine, and 1-naphthylamine.
Examples of the nitrogen-containing compound (II) include ethylenediamine, N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenyl ether, 4,4xe2x80x2-diaminobenzophenone, 4,4xe2x80x2-diaminodiphenylamine, 2,2-bis(4xe2x80x2-aminophenyl)propane, 2-(3xe2x80x2-aminophenyl)-2-(4xe2x80x2-aminophenyl)propane, 2-(4xe2x80x2-aminophenyl)-2-(3xe2x80x2-hydroxyphenyl)propane, 2-(4xe2x80x2-aminophenyl)-2-(4xe2x80x2-hydroxyphenyl)propane, 1,4-bis[1xe2x80x2-(4xe2x80x3-aminophenyl)-1xe2x80x2-methylethyl]benzene, 1,3-bis[1xe2x80x2-(4xe2x80x3-aminophenyl)-1xe2x80x2-methylethyl]benzene, and the like.
As examples of the nitrogen-containing compound (III), polyethyleneimine, polyallylamine, a polymer of dimethylaminoethylacrylamide, and the like can be given.
Examples of the amide group-containing compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, and the like.
Examples of the urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea, and the like. Examples of the nitrogen-containing heterocyclic compounds include imidazoles such as imidazole, benzimidazole, 4-methylimidazole, and 4-methyl-2-phenylimidazole; pyridines such as pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, N-methyl-4-phenylpyridine, nicotine, nicotinic acid, nicotinamide, quinoline, 8-oxyquinoline, and acridine; pyrazine, pyrazole, pyridazine, quinoxaline, purine, pyrrolidine, piperidine, morpholine, 4-methylmorpholine, piperazine, 1,4-dimethylpiperazine, 1,4-diazabicyclo[2.2.2]octane; and the like.
Of these nitrogen-containing organic compounds, the nitrogen-containing compound (I) and the nitrogen-containing heterocyclic compound are preferable. Trialkylamines are particularly preferable among the nitrogen-containing compound (I), and pyridines are particularly preferable among the nitrogen-containing heterocyclic compounds.
In the present invention, the acid diffusion controller can be used either individually or in combinations of two or more.
The amount of the acid diffusion controller to be used is usually 15 parts by weight or less, preferably 0.001-10 parts by weight, and still more preferably 0.005-5 parts by weight for 100 parts by weight of the resin (A). If the amount of the acid diffusion controller exceeds 15 parts by weight, sensitivity as a resist and developability of the exposed area tend to decrease. If the amount is less than 0.001 part by weight, the pattern shape or dimensional accuracy may decrease depending on the processing conditions.
Other Additives
Various additives such as surfactants and sensitizers can be optionally added to the radiation-sensitive resin composition of the present invention.
The surfactants improve the applicability or striation of the composition and developability as a resist.
Examples of surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate; and commercially available products such as FTOP EF301, EF303, EF352 (manufactured by TOHKEM PRODUCTS CORPORATION), MEGAFAC F171, F173 (manufactured by Dainippon Ink and Chemicals, Inc.), Fluorard FC430, FC431 (manufactured by Sumitomo 3M Ltd.), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Co., Ltd.), KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), and Polyflow No. 75, No. 95 (manufactured by Kyoeisha Chemical Co., Ltd.).
These surfactants may be used either individually or in combinations of two or more.
The amount of the surfactants to be added is usually 2 parts by weight or less for 100 parts by weight of the resin (A).
The sensitizers absorb the energy of the radiation and transmit the energy to the acid generator (B) or the other acid generators, thereby increasing the amount of acid to be generated upon exposure. The sensitizers improve the apparent sensitivity as a resist.
As preferable examples of the sensitizers, benzophenones, rose bengals, anthracenes, and the like can be given.
These sensitizers may be used either individually or in combinations of two or more. The amount of sensitizers to be added is usually 50 parts by weight or less for 100 parts by weight of the resin (A).
The addition of dyes or pigments, or both, visualizes the latent image of the exposed area to relax the effect of halation at the time of exposure. Use of adhesion adjuvants improves adhesiveness to the substrate.
As other additives, halation inhibitors such as 4-hydroxy-4xe2x80x2-methylchalcone, form improvers, storage stabilizers, antifoaming agents, and the like can be added.
Solvent
The radiation-sensitive resin composition of the present invention is prepared as a composition solution when used in practice by homogeneously dissolving the composition in a solvent so that the total solid concentration is 1-50 wt %, and preferably 3-40 wt %, and filtering the solution using a filter with a pore diameter of about 0.2 xcexcm.
As examples of the solvent used for preparing the composition solution, ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, and ethylene glycol mono-n-butyl ether acetate; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, and propylene glycol mono-n-butyl ether; propylene glycol dialkyl ethers such as propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, and propylene glycol di-n-butyl ether; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, and propylene glycol mono-n-butyl ether acetate; lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, and i-propyl lactate; aliphatic carboxylic acid esters such as n-amyl formate, i-amyl formate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-amyl acetate, i-amyl acetate, i-propyl propionate, n-butyl propionate, and i-butyl propionate; other esters such as ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, butyl 3-methoxyacetate, butyl 3-methyl-3-methoxyacetate, butyl 3-methyl-3-methoxypropionate, butyl 3-methyl-3-methoxybutyrate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate, and ethyl pyruvate; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, and cyclohexanone; amides such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, N,N-dimethyl acetamide, and N-methylpyrrolidone; lactones such as xcex3-butyrolactone; and the like can be given.
These solvents may be used either individually or in combinations of two or more.
Formation of Resist Pattern
The resist pattern is formed from the radiation-sensitive resin composition of the present invention by applying the above-described composition solution to a substrate such as a silicon wafer, wafer coated with aluminum, wafer coated with silicon nitride, or wafer coated with an organic lower layer reflection preventive film by rotational coating, cast coating, roll coating, and the like to form a resist film. The resist film is optionally treated by a pre-bake (hereinafter referred to as xe2x80x9cPBxe2x80x9d) at 70-160xc2x0 C. for 30 minutes or more. The resist film is then exposed through a specific mask pattern. As examples of the radiation used for exposure, i-rays (wavelength: 365 nm), far ultraviolet rays such as an ArF excimer laser (wavelength: 193 nm) and KrF excimer laser (wavelength: 248 nm), charged particle rays such as electron beams, X-rays such as synchrotron radiation, and the like are appropriately used depending on the type of acid generator (B) and the other acid generators. Of these, far ultraviolet rays and charged particle rays are preferable. The exposure conditions such as the amount of exposure are appropriately determined depending on the composition of the radiation-sensitive resin composition, type of additives, and the like.
In the present invention, it is preferable to perform a post-exposure bake (hereinafter referred to as xe2x80x9cPEBxe2x80x9d) after exposure at 70-160xc2x0 C., in particular, at 120-160xc2x0 C. for 30 minutes or more in order to steadily form, with high accuracy, a minute resist pattern which excels in resolution, developability, pattern form, PED stability, and the like. If the heating temperature for PEB is less than 70xc2x0 C., PED stability tends to decrease.
The exposed resist film is then developed using an alkaline developer at 10-50xc2x0 C. for 30-200 seconds to form a predetermined resist pattern.
As the alkaline developer, an alkaline aqueous solution prepared by dissolving at least one alkaline compound such as alkaline metal hydroxide, aqueous ammonia, mono-, di-, or tri-alkylamine, mono-, di-, or tri-alkanolamine, heterocyclic amine, tetraalkylammonium hydroxide, corrin, 1,8-diazabicyclo[5.4.0]-7-undecene, and 1,5-diazabicyclo[4.3.0]-5-nonene to a concentration of 1-10 wt %, and preferably 1-5 wt % is used.
Moreover, an appropriate amount of a water-soluble organic solvent such as methanol and ethanol or surfactants can be added to the developer comprising the above alkaline aqueous solution.
When using the developer comprising an alkaline aqueous solution, the resist film is washed with water after development.
When forming the resist pattern, a protective film may be provided on the resist film in order to prevent the effect of basic impurities and the like included in the environmental atmosphere.